package console_exporter

import (
	"context"
	"fmt"
	"sync"

	"git.ma-al.com/gora_filip/pkg/level"
	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/sdk/trace"
)

type TraceFormatter interface {
	FormatSpans(spans []trace.ReadOnlySpan, removeFields []attribute.Key, verbosityLevel level.SeverityLevel, addTraceId bool, onlyErrors bool) (string, error)
}

// Configuration for the exporter.
//
// Most of options are passed to the formatter.
type ExporterOptions struct {
	// Try to parse filters from an environment variable with a name provided by this field.
	// Result will only by applied to unset options. NOT IMPLEMENTED!
	FilterFromEnvVar *string
	// Filter the output based on the [level.SeverityLevel].
	FilterOnLevel *level.SeverityLevel
	// Fields that should be removed from the output.
	FilterOutFields []attribute.Key
	// Print only trace events instead of whole traces.
	EmitEventsOnly bool
	// Add trace id to output
	EmitTraceId bool
	// Print output only when an error is found
	EmitOnlyOnError bool
	// Used only when `EmitEventsOnly` is set to true.
	TraceFormatter *TraceFormatter
}

type Exporter struct {
	lvl            level.SeverityLevel
	removedFields  []attribute.Key
	addTraceId     bool
	onlyErrs       bool
	traceFormatter TraceFormatter
	printerMu      sync.Mutex
	stoppedMu      sync.RWMutex
	stopped        bool
}

func NewExporter(opts ExporterOptions) trace.SpanExporter {
	var formatter TraceFormatter
	var lvl level.SeverityLevel

	if opts.TraceFormatter != nil {
		formatter = *opts.TraceFormatter
	} else {
		formatter = TraceFormatter(&EventsOnlyFormatter{})
	}
	if opts.FilterOnLevel != nil {
		lvl = *opts.FilterOnLevel
	} else {
		lvl = level.TRACE
	}

	return &Exporter{
		traceFormatter: formatter,
		removedFields:  opts.FilterOutFields,
		addTraceId:     opts.EmitTraceId,
		onlyErrs:       opts.EmitOnlyOnError,
		lvl:            lvl,
	}
}

// Implements [trace.SpanExporter]
func (e *Exporter) ExportSpans(ctx context.Context, spans []trace.ReadOnlySpan) error {
	e.stoppedMu.RLock()
	stopped := e.stopped
	e.stoppedMu.RUnlock()
	if stopped {
		return nil
	}
	if len(spans) == 0 {
		return nil
	}

	e.printerMu.Lock()
	defer e.printerMu.Unlock()
	printLine, err := e.traceFormatter.FormatSpans(spans, e.removedFields, e.lvl, e.addTraceId, e.onlyErrs)
	if err != nil {
		fmt.Printf("FAILED TO FORMAT A TRACE WITH ERR: %#v\n", err)
	}
	if len(printLine) > 0 {
		fmt.Println(printLine)
	}

	return nil
}

// Implements [trace.SpanExporter]
func (e *Exporter) Shutdown(ctx context.Context) error {
	e.stoppedMu.Lock()
	e.stopped = true
	e.stoppedMu.Unlock()

	select {
	case <-ctx.Done():
		return ctx.Err()
	default:
	}
	return nil
}